Traveling for Thanksgiving? Meteorologists warn of winter storms.

The weather is expected to become particularly hazardous on Wednesday, the biggest travel day of the year.

Weather Underground via AP

This NOAA satellite image taken Saturday, Nov. 21, 2015, at 1:00 AM EDT shows mostly clear skies and fair weather dominating the western United States due to a large surface ridge. Some scattered snow showers are also moving over Colorado and the Central Plains along the tail end of an upper level trough that is progressing across the Northern Plains into the Midwest. Tropical Storm Rick is in the bottom right corner with maximum sustained winds of 40 miles per hour. This tropical system is moving west-northwest at 13 miles per hour with poorly organized convection. (Weather Underground via AP)

Nearly 50 million Americans will pack up their bags for Thanksgiving this year, the most since 2007, according to AAA. But for some who are headed West, the weather may not be in your favor.

A winter storm, likely exacerbated by El Niño, kicks off this week with a blast of Arctic air sweeping the West and Plains states, according to Weather.com.

The weather is expected to become particularly hazardous on Wednesday, the biggest travel day of the year.

"We could have freezing rain and ice through the Plains states into Friday," Brian Fortier, a senior meteorologist at the Weather Channel, told NBC News.

Northern Idaho, Montana, and northeastern Washington have all been issued winter storm watches. That includes Spokane, where more than 30,000 customers are still without power nearly a week since a windstorm wreaked havoc there.

Western Oklahoma, the Texas Panhandle, and Kansas will likely see snow and ice.

And a cold front will sail over the Pacific Northwest Monday and Tuesday, likely bringing precipitation along with it. By midweek, the low-pressure system will drop snow over the central and northern Rockies, potentially reaching the valley floors.

Portland and Seattle will have rain showers Monday through Tuesday while the Cascades will see snowfall.

The West Coast will likely experience rainstorms, especially southern and central California on Tuesday, potentially into Wednesday.

San Francisco International Airport will likely see temperatures in the 30s, while overnight low temperatures will be in the single digits for parts of the northern and central Rockies on Thursday morning into Saturday.

Besides the weather, some fear the recent terror attacks in Paris have law enforcement on high alert, potentially making security protocols more stringent. But Secretary of Homeland Security Jeh Johnson told NBC’s "Meet the Press" that Americans should keep to their holiday plans.

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"With this holiday season coming up we want the public to continue to go to public events, celebrate the holiday season, travel, be with their families and the like," Johnson said.

On Tuesday, The Christian Science Monitor published the top ten essential tips for flying this Thanksgiving. Among the suggestions includes arranging a back-up ticket, checking to make sure your pet isn’t disqualified from flying, and giving your bags extra tags – inside and out.

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